A failing or contaminated rear oxygen sensor. A real rich condition. Oil or coolant burning.

P2271 O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 2)

Q: What does P2271 mean?

P2271 means bank 1's rear oxygen sensor won't read lean when tested, usually a lazy or contaminated sensor. The rear oxygen sensor on bank 1 isn't dropping to lean when the engine computer cuts fuel to test it (often during deceleration). The sensor is usually lazy or contaminated.

Oxygen sensors

P2271 means bank 1's rear oxygen sensor won't read lean when tested, usually a lazy or contaminated sensor.

The rear oxygen sensor on bank 1 isn't dropping to lean when the engine computer cuts fuel to test it (often during deceleration). The sensor is usually lazy or contaminated.

Can I keep driving? Yes, for now.

Safe to drive for now. It affects the catalytic converter check and emissions.

Common causes

A failing or contaminated rear oxygen sensor
A real rich condition
Oil or coolant burning

Symptoms

Check-engine light
Sometimes poor fuel economy

What to check first

Check for rich codes and fix them first.
Watch the rear sensor during deceleration; it should drop low.
Replace the sensor if it stays high.

What does P2271 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P2271

No scanner? Most auto parts stores read check-engine codes for free.

Related codes

General guidance for P2271 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.